High-frequency tube structure



iatented Apr. 22, 1952 Arthur E..Harrison, Princeton, N. J., assignor to The Sperry Corporation, a corporation of Delaware originsi application antes 29, 1942; Serial No. 428,682. "Divide'dfand this" application December 14, '194 6, Serial N0. 716,320

(01. sit- 8 Claims.

The present invention relates,generally to ultra-high-frequency. tube structurev and more particularly to improvements in .ultra-high-freuuency devices of the reflected electron beam type such as disclosed in Fig. 2 of ,Varlan Patent No. 2,250,511 granted July 29,1941. The present invention is a division of applioation SerialNo.

' 128,682 filedJanuary 29, 19 42. and which issued 21,

as U. S. Patent No. 2,414,785, dated January Electron discharge devices utilizing a cavity resonator, through which an electron stream is projected for velocity modulation and thereafter is reprojected under the influence of a reflecting electrode structure to sust'ain. oscillations within the resonator, are now generally termed jreflex l-zlystrons. A principal object of the presentinvention is to provide improvements in velocityniodulated tubes, especially of the reflex klystron type, for providing focusingof the reflected electron beam and therefore improving the operating efficiency. o o

Another object of the present invention is,;to provide means in a reflex klystron-for focusing the returned or reflectedelectronbeam, as byan electrode disposed between the resonator and the reflector electrode.

A further object of the present invention isfto provide improved resonator constructions. for

ultra-high-irequency tubes permitting satis'fac- Fig. 2 is a similar view taken at right angles to that ofFig.1; ,7

Fig. 3 is a cross-sectional view of the devices of Figs. 1 and 2 along line 33 thereof.

Referring to the drawings, aresonant chamber or cavity resonator 92 is provided in .thefo'rm of a round conducting disc 93 which is turnedor otherwise suitably formed, into a substantially cylindrical cavity, having an, end wall 94 which is centrally apertured and carries an exit grid 95,

where such grid is used. A flexibleconducting diaphragm 96 closes the other end of the resonator 92 and carries a reentrant apertured member having a cylindrical portion l0! and a tapered or frusto-conical portion 91 reentrant into the resonator 92.

q Reentrant tapered portion 97 carries an entrance grid 98 which, when used, is placed .con-

centric with and close to exit grid 95. As shown in Fig. 3, grids and 98 may consist of radial conducting long and short wires 99 and-1B0 which may be inserted into wall 94 and reentrant memberfilby placing in milled radial slots'in the uppersurfaces of members 94 and 91. Thereafter hydraulic pressure applied to these upper surfaces will cause the surface metal to flow over the. wires, thus staking them in position. Any other method may be used which will leave relatively smooth surfaces after the grids are inserted. n

Outside of the resonator 92, reentrant portion 9'5 may be extended as a tubular portion lfll provided with a flange I02 which cooperates with a similarv flange Hi3 attached to the resonator body 93- to provide any desired tuning mechanism for resonator," such as that shown in Fig. 1 of the above-mentioned parent application, for example.

, -A cathode 104 is provided having its emitting surface placed close to entrance grid 98 and well inside of tubular portion IUI. This cathode IM may be similar to that illustrated in Figs. 9-11 or 14 of the parent application, .and may besurrounded by a tubular focusing shield I05 extended past emitter I 04 toward the entrance grid 98- and supplieclwith a voltage relative to cathode I04 sufi'icient to give slight convergence to theresultant electron beam. Focusing shield I05 is supported from and supplied with proper voltage by. leads I06 passing through a glass press or seal I01.

A reflectorplate is provided in the form of a flat disc I30 supported from an upper glass bell or press 8| by a lead-in strut 82. Reflector disc is surrounded by a concentrically positioned focusing ring. 13! supported from lead-in struts 12!. Ring l3l. imparts a slight focusing effect to the electrons on their return trip toward exit grid 95,-so, that fewer returning electrons strike thebutside resonator wall 94 and moreelectrons re;enter resonator 92 to yield useful energy thereto. Reflector disc I 30 is preferably operated, at o r, near the potential of cathode, I04, and focusing ring 3| may be slightly positive or negative with respect to disc I36.

-An output coaxial line terminal Ill through which ultra-high-frequency energy may be removed from resonator 92 is shown coupled thereto by a coupling loop I09. It will be understood that a glass seal I I3 between the inner conductor H6 and the outer conductor N2 of terminal ii! is provided for maintaining the internal vacuum.

It is evident that any desired number of such coupling loops and concentric line terminals may be provided.

When using very short wavelengths, difficulty is often experienced in obtaining a broad tuning range by varying the grid separation, due to the fact that the relatively small resonator sizes consequent upon the short wavelength, prevent large variations in grid spacing. Under these conditions, the construction shown in Figs. 1-3 may advantageously be used. In this figure, two conductive members I29, I29 in the form of axial non-diametric sections of a disc are inserted against resonator walls 94 and 93, leaving a small free space above diaphragm 96 to permit its motion. The resultant elimination of complete axial symmetry in the resonator produces a situation where, for a given resonant frequency, the size of the resonator is enlarged, permitting a larger diaphragm 96 and thereby permitting an extended tuning range.

It will be understood, of course, that the focusing ring I3I need not be used simultaneously with the plugs I29, I29, but may be used even where plugs I29, I29 are omitted, and vice versa.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A cavity resonator comprising a conductive cylindrical casing lportion forming an enlarged portion of a resonant chamber, body means thereon forming a constricted portion of said resonant chamber, said portions being located adjacent one another forming said resonant chamber, and apertured end walls connected to the outer ends of said casing portion and said body means, one of said end Walls being flexible to facilitate the adjustment of the resonant frequency of said resonant chamber.

2. A high frequency tube structure comprisin a cavity resonator having a pair of apertured walls, means positioned on one side of and concentric with said apertured walls for passing a stream of electrons through said resonator by way of said apertured walls, means positioned on the other side of and concentric with said apertured walls including a reflector electrode for redirecting said electrons back through said resonator, and means projecting in said resonator for increasing its resonant frequency without changing the outer dimensions of the resonator.

3. A reflex klystron comprising a cavity resonator having an electron permeable region, an electron emitter aligned therewith, a flat discshaped reflector electrode aligned with said emitter, said electron emitter and said reflector electrode being positioned on opposite sides of said region, whereby an electron beam traverses said region, and a cylindrical-focusing electrode concentric with and in part surrounding said reflector electrode, said focusing electrode being farther positioned in close proximity to the path of said electron beam.

4. A reflex klystron comprising cavity resonator means having electron-permeable foraminate first and second grids aligned along an axis, means for projecting and reflecting an electron beam only in a dual traverse of said resonator means, said electron projecting and reflecting means including an electron source, said electron source being adjacent said first grid and aligned along said axis, said electron projecting and reflecting means further including a reflector electrode, said reflector electrode being adjacent said second grid and being aligned along said axis, and a focusing electrode aligned along said axis and partially disposed intermediate said reflector electrode and said second grid of said resonator means.

5. Apparatus as in claim 4 further including means in said resonator means for destroying axial symmetry thereof, whereby said resonator means may have a wider tuning range.

6. Apparatus as in claim 3 wherein tubular means are provided substantially concentric with and partially surrounding said focusing means, said tubular means defining a portion of the vacuum envelope of the klystron.

'7. A high frequency tube structure having an axis comprising a conductive casing having a substantially right-circular cylindrical inner surface aligned along said axis, said casing further having end wall means with portions thereof substantially perpendicularly disposed to said axis, said end wall means further having centrally-disposed electron-permeable regions, said surface of said casing and the opposed surfaces of said end wall means forming a chamber, an electron source for providing electrons for projection through said regions, a reflector electrode aligned along said axis for reversing said electrons and redirecting said electrons through said regions, and a conductive block positioned withinsaid chamber out of the path of said electrons and connected to a portion of said chamber, the exposed surfaces of said block and chamber providing a resonator which is asymmetrical with respect to said axis.

8. A velocity-modulated generator of the reflex type comprising an electron emissive cathode, a resonant member adjacent thereto having apertured wall portions, a reflector electrode disposed on the opposite side of said resonant member from said cathode, and a focusing electrode concentric with and partly surrounding said reflector electrode.

ARTHUR E. HARRISON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,106,769 Southworth Feb. 1, 1938 2,180,950 Bowen Nov. 21, 1939 2,199,083 Schelkunofi Apr. 30, 1940 2,259,690 Hansen et a1 Oct. 21, 1941 2,293,151 Linder Aug. 18, 1942 2,306,282 Samuel Dec. 22, 1942 2,342,789 Cassen Feb. 29, 1944 2,356,414 Linder Aug. 22, 1944 2,421,790 Korman June 10, 1947 

